MONOGEAPH OP THE EXISTING CBINOIDS. 



243 



the centrodorsal is relatively longer; again the radical resorption may be, as in 

 Zenometra (figs. 214-216, p. 241) and in Balanometra, entirely restricted to the 

 midradial areas, leaving the interradial areas standing up as high ridges and 

 making the centrodorsal appear far larger than it really is. 



Fig. 217. 



Fn. 220. 



Fig. 218. 



Fig. 219. 



Fig. 221. 



Fig. 222. 



Fig. 225. 



Fig. 224. 



Fio. 226. 



Figs. 217-226.— 217, Dorsal view of the centrodorsal of a specimen- of Zenometra columnaris from Georgia. 218. 

 Lateral \-iew of the centrodorsal of a sPEaMEN of .Vteleceinl-s balanoides from Porto Rico. 219, Dorsal vjew 

 of the centrodorsal of a specimen of Leptometra celhca (after r. U. Carpenter). 220, Lateral -view of the 

 centrodorsal of a specimen of Trichometra ^^D.xATOR from the I1aw,ui.vn Islands, 221, Lateral nEW or the 

 centrodorsal of a specimen of Trichometra aspera from Georgu. 222, Lateral ■\-iew or the centrodor.sal or a 

 specimen of Trichometra odscura from southern India. 223, Lateral view of the centrodorsal of a specimen 

 of .\telecrinus conifer from the Hawaiian Islands. 224, Lateral \nEW of the centrodorsal of a specimen or 

 Trichometra e.xplicata from the Philippine Islands. 225 Dorsal view or the centrodorsal of a specimen or 

 Florometra asperrima from Alask.\. 226, Lateral mew of the centrodorsal of a specimen of Florometba 

 asperrima from Alaska. 



In the families Zygometrida? (figs. 83, p. 136, and S4, p. 137), Ilimerometridffi 

 (figs. 85, p. 139, 86, p. 141, and 1S4-1S6, p. 235), Stephanometridiv, Mariamet- 

 ridje (fig. 432, p. 349), Colobometridje (fig. 87, p. 143), Troiiioinctrida; (figs. 88, 

 p. 145, and 303, p. 264), and Calometridffi (fig. 89, p. 147) the centrodorsal is 



